

66 



THE SPONGES. 



to Schulze's figure of Farrea occa (1887, Plate LXXIL, Fig. 3), I find that 

 the rounded tongue-like outgrowths, which project toward one another, 

 consist in part of but one layer of beams. The free edges of the lateral 

 cups, in these dried specimens, have commonly a conspicuously thickened 

 appearance, due to the great number of dermal pinuli which are here 

 massed together. 



In my specimens the dictyonal framework shows the usual difference 

 between the gastral and dermal surfaces, and the radial processes on the 

 latter surface are frequently bifid. 



* 



The dermal pinules (Fig. 3, Plate 8) closely resemble the corre- 

 sponding spicules of the type. Very commonly all six rays are about 

 equal in length, although the proximal ray or more rarely the distal ray 

 may be the longest. The bushy distal ray has a relatively long, bare 

 basal portion which is cylindrical and is always slightly thicker than the 

 corresponding parts of the other rays. The proximal and tangential rays 

 taper evenly toward the pointed ends, where they are roughened, else- 

 where smooth. The measurements of a characteristic spicule are : distal 

 ray, 160 /x long with a greatest thickness of 36 /x, and a bare basal part 

 50 jji long and 10 /x thick ; tangential and proximal rays, 160 xt x 8 /x. 

 The rays may only be 100 /x long, proximals and tangentials then having 

 a basal thickness of 6-7 /x, the distal a basal thickness of 8 xt. In some 

 spicules the bushy distal ray, the characteristic appearance of which is 

 given in the figure, may be thin and nearly cylindrical, bearing spines 

 which are considerably shorter and sparser than in the typical form. 



The gastralia, Figs. 2 and 6, Plate 8, include both pentact and hexact 

 forms. The former in most of the specimens are much the more abun- 

 dant, while in two of the specimens they are scarcely more abundant 

 than the hexacts. The two forms are alike except as regards the distal 

 ray. In the pentacts, the distal ray is represented by a boss which is small 



and of an irregular, angular shape. In the hexacts the distal ray, which 

 is of varying length, up to 120 /x, may be nearly cylindrical or consider- 

 ably swollen. 

 Plate 8. 



Characteristic conditions are shown in Figs. 2 and 6, 



The 



tangential 



rays, which measure about 250 /x x 16 



20 /x, have large blunt or rounded teeth on the distal surface and sides, 

 while the proximal surface is nearly smooth, having only a very few such 



* 



teeth. The rays curve in very slightly, are often nearly straight, taper 

 evenly and slightly toward the end, which is blunt or rounded and not 



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